The present invention relates to a rain gauge for collecting and measuring precipitation and, in particular, to a rain gauge that shows the amount of collected precipitation that has evaporated. The rain gauge of the present invention also allows for the measurement of precipitation during an interim period of time without discharging the precipitation already collected.
A common type of rain gauge utilizes a transparent tube to collect precipitation. The tube is usually marked on an outer surface to visually indicate the water level in the tube. A problem with such a rain gauge is that the collected precipitation may evaporate, leading to inaccurate water level readings. Therefore, some rain gauges use a non-evaporating liquid that floats on top of the collected precipitation to prevent the evaporation of the collected precipitation, as shown in Hunn U.S. Pat. No. 2,507,206.
Some non-evaporating liquids do not completely prevent the evaporation of collected precipitation. It is therefore advantageous to have a rain gauge that measures the amount of evaporation, enabling a more accurate water level reading. It is also advantageous to be able to measure the amount of precipitation that accumulates during an interim period of time without having to discharge the previously accumulated precipitation or record water levels on paper.